root/arch/sh/lib/__clear_user.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * __clear_user_page, __clear_user, clear_page implementation of SuperH
   4  *
   5  * Copyright (C) 2001  Kaz Kojima
   6  * Copyright (C) 2001, 2002  Niibe Yutaka
   7  * Copyright (C) 2006  Paul Mundt
   8  */
   9 #include <linux/linkage.h>
  10 #include <asm/page.h>
  11 
  12 ENTRY(__clear_user)
  13         !
  14         mov     #0, r0
  15         mov     #0xffffffe0, r1
  16         !
  17         ! r4..(r4+31)&~32          -------- not aligned [ Area 0 ]
  18         ! (r4+31)&~32..(r4+r5)&~32 -------- aligned     [ Area 1 ]
  19         ! (r4+r5)&~32..r4+r5       -------- not aligned [ Area 2 ]
  20         !
  21         ! Clear area 0
  22         mov     r4, r2
  23         !
  24         tst     r1, r5          ! length < 32
  25         bt      .Larea2         ! skip to remainder
  26         !
  27         add     #31, r2
  28         and     r1, r2
  29         cmp/eq  r4, r2
  30         bt      .Larea1
  31         mov     r2, r3
  32         sub     r4, r3
  33         mov     r3, r7
  34         mov     r4, r2
  35         !
  36 .L0:    dt      r3
  37 0:      mov.b   r0, @r2
  38         bf/s    .L0
  39          add    #1, r2
  40         !
  41         sub     r7, r5
  42         mov     r2, r4
  43 .Larea1:
  44         mov     r4, r3
  45         add     r5, r3
  46         and     r1, r3
  47         cmp/hi  r2, r3
  48         bf      .Larea2
  49         !
  50         ! Clear area 1
  51 #if defined(CONFIG_CPU_SH4)
  52 1:      movca.l r0, @r2
  53 #else
  54 1:      mov.l   r0, @r2
  55 #endif
  56         add     #4, r2
  57 2:      mov.l   r0, @r2
  58         add     #4, r2
  59 3:      mov.l   r0, @r2
  60         add     #4, r2
  61 4:      mov.l   r0, @r2
  62         add     #4, r2
  63 5:      mov.l   r0, @r2
  64         add     #4, r2
  65 6:      mov.l   r0, @r2
  66         add     #4, r2
  67 7:      mov.l   r0, @r2
  68         add     #4, r2
  69 8:      mov.l   r0, @r2
  70         add     #4, r2
  71         cmp/hi  r2, r3
  72         bt/s    1b
  73          nop
  74         !
  75         ! Clear area 2
  76 .Larea2:
  77         mov     r4, r3
  78         add     r5, r3
  79         cmp/hs  r3, r2
  80         bt/s    .Ldone
  81          sub    r2, r3
  82 .L2:    dt      r3
  83 9:      mov.b   r0, @r2
  84         bf/s    .L2
  85          add    #1, r2
  86         !
  87 .Ldone: rts
  88          mov    #0, r0  ! return 0 as normal return
  89 
  90         ! return the number of bytes remained
  91 .Lbad_clear_user:
  92         mov     r4, r0
  93         add     r5, r0
  94         rts
  95          sub    r2, r0
  96 
  97 .section __ex_table,"a"
  98         .align 2
  99         .long   0b, .Lbad_clear_user
 100         .long   1b, .Lbad_clear_user
 101         .long   2b, .Lbad_clear_user
 102         .long   3b, .Lbad_clear_user
 103         .long   4b, .Lbad_clear_user
 104         .long   5b, .Lbad_clear_user
 105         .long   6b, .Lbad_clear_user
 106         .long   7b, .Lbad_clear_user
 107         .long   8b, .Lbad_clear_user
 108         .long   9b, .Lbad_clear_user
 109 .previous